The invention was designed as part of a personal communicator that combines a cellular phone, data and fax modem, and a data processing system, into a mobile, compact, lightweight, battery operated, handheld device having a variety of data processing and communication functions. These functions include operating the device as a standard cellular phone; a calendar showing a list of things to do at various times; an address book for organizing names, addresses and phone numbers; an editor allowing text entry and editing; a calculator; and a communication device for fax, E-mail and various data bases and services.
The personal communicator is in the form of a handset having an earphone or speaker at one end and a microphone at the other end. The speaker and microphone are spaced apart the same distance as the distance between an ear and the mouth of an "average" user, to facilitate use of the communicator as a cellular phone. A small touchscreen display is located between the speaker and the microphone. The display has a fine pitch liquid crystal display (LCD) allowing it to be operated as a standard CGA with a resolution of 640.times.200 pixels. The touch sensitive display provides a graphic user interface and is used as an input/output device for a variety of functions or applications.
Within the prior art, particularly that of desktop personal computers, it is publicly known to control pan and zoom functions on graphic images by positioning a cursor with the aid of a cursor control device such as a keyboard, mouse, trackball, pen, etc. With a mouse controlled screen, a common zoom function is to click at one corner of the area to be magnified, and drag the mouse to another corner. Upon release, the delineated area is magnified. Panning is done by moving the cursor against the edge of a screen image. U.S. Pat. No. 5,187,776- Yanker discloses an "IMAGE EDITOR ZOOM FUNCTION" for a personal computer CRT display, in which a small viewport window shows an image at a (1.times.) magnification. The viewport is superimposed on a larger display of a magnified portion of the image centered about the location of the cursor in the viewport. The cursor is also movable in the viewport to pan the magnified image.
U.S. Pat. No. 4,899,292- Montagan et al, discloses a "SYSTEM FOR STORING AND RETRIEVING TEST AND ASSOCIATED GRAPHICS". The system includes a computer coupled to a terminal having a resistive touchscreen. A wand is connected to an analog to digital converter. When the wand is touched to the screen, it detects a voltage signal that is converted into coordinates. The image is magnified by two centered at the point of touch.